Field of the Invention
The present invention concerns the field of microwave technology. Said invention relates to a microwave cable as claimed in the preamble of claim 1. Said invention further relates to a method for producing said microwave cable, and also to the use of a microwave cable of this kind.
Discussion of Related Art
Cabling technology discloses a large number of solutions in respect of how a cable of this kind, when it comprises inner conductors and outer conductors, can be designed.
Document U.S. Pat. No. 2,691,698 describes, for example, a telephone cable which, in addition to a large number of inner conductors, has two outer conductors which are insulated from one another and which are designed as tapings comprising a metal foil. In this case, the outer conductors are used to separately transmit signals.
Document U.S. Pat. No. 2,447,168 discloses a high-frequency cabling in the case of which two inner conductors are enclosed by a dielectric, and two tapings comprising metallized paper are applied to the dielectric one above the other.
Document U.S. Pat. No. 5,214,243 discloses a coaxial cable having a central inner conductor, a dielectric, a layer of wound PTFE tape which is applied to said dielectric, a metal wire mesh which is applied over said layer of wound PTFE tape, a braiding of polyamide fibers which is applied over said metal wire mesh, and finally two tapings comprising PTFE tape which are wound in opposite directions in an overlapping manner.
Finally, document U.S. Pat. No. 6,201,190 describes a coaxial cable in which the dielectric which surrounds the inner conductor is enclosed by two foil tapes which are situated one above the other. In this case, the foil tapes are in the form of aluminum/polyester/aluminum laminates.
These solutions have the disadvantage, especially in the microwave frequency range at frequencies of 40 GHz and above, that it is not possible to manufacture assembled (coaxial) cables with optimum electrical parameters.
In the case of a tape which is wound once, the insertion loss during bending or twisting is unstable because the windings of the tape shift or loosen. In addition, a (coaxial) plug connector which is fitted to the cable end can be matched to a cable of this kind only to a limited extent because the tape can become loose, and therefore no longer bear tightly, after insulation is stripped from the cable end.
Although it is possible to largely prevent the winding (taping) from becoming detached from a cable end when the tape is wound in an overlapping manner because the end of the tape is fixed by the overlapping at the cable end on which the winding progresses in the cable longitudinal direction, fixing of this kind is not provided at the other cable end, and therefore the taping becomes slightly loose or even detached at said cable end.
This has an adverse effect on RF matching to the plug connector, and the stability of this cable section with loosened tape is also impaired.